Abstract: A method, and a system for implementing such method, for use in a magnetic disk storage system for compensating for variation in spin speed of a data storage media from a nominal or design spin speed. The method includes providing the nominal spin speed for the data storage media in the particular magnetic disk storage system and then measuring the actual spin speed of the data storage media. In one preferred embodiment, the spin speed measurement is completed by measuring the time from one servo position field to the next sequential servo position field in a track on the data storage media. Next, the present spin speed variation is determined by comparing the measured spin speed with the nominal spin speed. A correction factor is calculated based on the spin speed error and applied to at least one data transfer parameter, such as channel reference frequency or read/write gate assertion timing, prior to a subsequent data transfer process (i.e., a read or a write operation).

Abstract: Disclosed is a storage media defect management method for use in a storage device that is to be coupled to a computer. The method broadly includes writing data to a storage media of the storage device, the storage media having a plurality of servo fields. Stopping the writing upon detecting an off-track or other servo field error with a particular servo field of the plurality of servo fields. Reallocating a plurality of suspect sectors that may be affected by the off-track or other servo field error detected in the particular servo field. The method then proceeds to resume the writing beginning with a next sector following the plurality of suspect sectors that were reallocated. In a preferred implementation, a number of preliminary checks are preferably performed on the plurality of suspect sectors to ascertain which ones may not be part of the reallocation transfer.

Abstract: Disclosed is a storage media defect management method for use in a storage device that is to be coupled to a computer. The method broadly includes writing data to a storage media of the storage device, the storage media having a plurality of servo fields. Stopping the writing upon detecting an off-track or other servo field error with a particular servo field of the plurality of servo fields. Reallocating a plurality of suspect sectors that may be affected by the off-track or other servo field error detected in the particular servo field. The method then proceeds to resume the writing beginning with a next sector following the plurality of suspect sectors that were reallocated. In a preferred implementation, a number of preliminary checks are preferably performed on the plurality of suspect sectors to ascertain which ones may not be part of the reallocation transfer.

Abstract: A method and data structure for a header-formatted defective sector management system. A spare sector is allocated for each n sectors. When a defective one of the n sectors is identified, the sectors are slipped using the spare sector. The location of the defective sector and the type of defect, e.g., data field or header field, is indicated by a data structure written to the header field of at least one of the non-defective sectors. When a second defective sector is identified, the system operates to disposition the second defective sector based on the type of the first defective sector. If the first defective sector was a defect in the data field and the second defective sector is a defect in the header field then the first defective sector is converted to a reassigned sector and the second defective sector is slipped. This avoids the problem of reassigning a sector having a defective header field.

Abstract: A system for halting operation of a hard disk controller when a write operation occurs during a servo positioning error condition including a memory cell for retaining an indication of whether a write operation occurred during the previous servo sector. A memory cell, such as a flip flop, is set on any occurrence of a write operation. With the reading of a next servo field, the output of the first flip flop is latched to a second flip flop. During a present servo sector, a servo positioning error signal is logically AND'ed with a write gate active signal where the write gate active signal is enabled if write gate is active in the present servo sector or write gate was active in the previous servo sector (as indicated by the output from the second flip flop.

Abstract: System and method for preventing multiple vends in which a customer gets more than one product for the price of one. The invention is applicable to vending machines having separate vend motors for delivering different products, with product selection switches for selectively energizing the vend motors. When one of the vend motors is energized, energization of a second vend motor is inhibited for a predetermined period of time to prevent vending of a second product.